A metal expansion joint for low temperature environment

Abstract

The present invention relates to the technical field of metal expansion joint auxiliary, and discloses a metal expansion joint for use in a low-temperature environment, comprising a metal expansion joint assembly, wherein an evenly distributed over-compensation protection assembly is fixedly installed on the outside of the metal expansion joint assembly, a cooling assembly is fixedly installed on the bottom end of the metal expansion joint assembly, the metal expansion joint assembly is used to connect pipelines at both ends, and compensate for the length of the pipelines through its own deformation function, the over-compensation protection assembly is used to provide an over-compensation protection function adapted to the fluid pressure in the pipeline, the cooling assembly is used to perform cooling protection on the metal expansion joint assembly, the metal expansion joint assembly comprises an upper flange plate, a lower flange plate is provided below the upper flange plate, the upper flange plate and the lower flange plate are symmetrical up and down, and evenly distributed threaded holes are provided on the upper flange plate and the lower flange plate, the device has an over-compensation protection function adapted to the fluid pressure in the pipe, and the device has a temperature cooling function for the fluid in the pipeline.

Description

Technical Field

[0001] The invention relates to the technical field of metal expansion joint auxiliary, and more particularly to a metal expansion joint used in a low temperature environment. Background Art

[0002] Metal expansion joints are a type of compensating device used in piping systems. Their main working principle is to use the expansion and contraction of metal materials to absorb the stress and deformation caused by temperature changes, vibration or deformation in the piping system, thereby protecting the normal operation of the piping system.

[0003] When the pipeline is deformed due to the pressure or temperature of the fluid in the pipeline, the metal expansion joint will expand and contract along its axial direction to compensate for the length of the pipeline. However, the metal expansion joint under the existing technology still has the following shortcomings when used:

[0004] First, in order to prevent the metal expansion joint from exceeding the allowable compensation amount when in use, a protective tie rod is generally provided at the flanges at both ends of the bellows connection. However, when the fluid pressure in the pipeline is too high, the tension on the protective tie rod is too large, and long-term use will cause damage to the tie rod, thereby affecting its service life. The metal expansion joint in the prior art does not have an over-compensation protection function that is adapted to the fluid pressure in the pipe.

[0005] Secondly, when the low-temperature metal expansion joint under the prior art is in use, when the temperature of the fluid in the pipeline is too high, the bellows of the metal expansion joint will be deformed due to the high temperature. Generally, the low-temperature metal expansion joint is suitable for the situation where the ambient temperature of the fluid in the pipe is relatively low. When the fluid temperature is too high, it is easy to cause damage to the metal expansion joint. The low-temperature metal expansion joint under the prior art does not have the function of reducing the pipe temperature of the bellows.

[0006] Therefore, in order to solve the above problems, it is necessary to provide a metal expansion joint for use in low temperature environments. Summary of the invention

[0007] In order to overcome the above-mentioned defects of the prior art, the present invention provides a metal expansion joint for use in a low-temperature environment to solve the problems existing in the above-mentioned background technology.

[0008] The present invention provides the following technical solutions: a metal expansion joint for low temperature environment, comprising a metal expansion joint assembly, the outside of the metal expansion joint assembly is fixedly installed with evenly distributed over-compensation protection assemblies, the bottom of the metal expansion joint assembly is fixedly installed with a cooling assembly, the metal expansion joint assembly is used to connect pipelines at both ends and compensate for the length of the pipelines through its own deformation function, the over-compensation protection assembly is used to provide an over-compensation protection function adapted to the fluid pressure in the pipeline, and the cooling assembly is used to cool the metal expansion joint assembly;

[0009] The metal expansion joint assembly includes an upper flange plate, a lower flange plate is provided below the upper flange plate, the upper flange plate and the lower flange plate are symmetrical up and down, and both the upper flange plate and the lower flange plate are provided with evenly distributed threaded holes, a protection rod is connected between the upper flange plate and the lower flange plate, both ends of the protection rod are threaded with protection nuts, the bottom of the upper flange plate is fixedly connected with a sleeve, the bottom end of the sleeve is fixedly connected with a bellows, the bottom end of the bellows is fixedly connected to the lower flange plate, the sleeve is provided with evenly distributed pressure relief holes, and pressure relief valves are fixedly installed in the pressure relief holes. The bellows will undergo axial deformation due to the pressure and temperature of the fluid in the pipeline, thereby providing length compensation for the pipeline system, and the protection rod can provide it with an over-compensation protection function to prevent it from excessive deformation.

[0010] Furthermore, the over-compensation protection component includes a bottom connecting column, which is threadedly sleeved with the threaded holes opened on the lower flange plate respectively, and a through hole is opened in the bottom connecting column. The upper end of the bottom connecting column is fixedly sleeved with a column sleeve, and the column sleeve is connected to the through hole.

[0011] Furthermore, the column sleeve is fixedly connected with a cavity column, the cavity column is movably connected with a piston shaft, the upper end of the piston shaft is fixedly connected with an upper connecting column, the upper connecting column is threadedly connected with the threaded holes opened on the upper flange plate, and the upper end of the cavity column is provided with an external leakage hole.

[0012] Furthermore, a thin shaft is fixedly connected to the bottom end of the upper connecting column, and a sealing piece is provided at the bottom end of the thin shaft, and the sealing piece is located in the upper inner space of the cavity column, and the shaft diameter of the thin shaft is smaller than the aperture of the leakage hole, and the leakage hole can be completely blocked when the sealing piece moves to the uppermost end; a pressure relief pipe is connected to the upper end of the cavity column, and the pressure relief pipe is communicated with the upper end space of the cavity column, and the pipeline of the pressure relief pipe is fixedly sleeved with the corresponding pressure relief hole, and under the action of the fluid pressure, the bellows undergoes axial deformation to provide length compensation for the pipeline, and during its deformation process, the distance between the upper flange plate and the lower flange plate is gradually increased. As the pressure gradually increases, the piston shaft begins to move upward in the cavity cylinder. At this time, the gas or fluid in the upper space of the cavity cylinder will be discharged outward through the leakage hole, thereby maintaining the air pressure in the upper space of the cavity cylinder stable. When the pressure of the fluid flowing through the inside of the bellows is too high and causes the bellows to reach its maximum allowable deformation, the pressure relief valve opens and the sealing piece moves to the upper end to completely block the leakage hole. The fluid will pass through the pressure relief valve and the pressure relief hole and enter the upper space of the cavity cylinder through the pressure relief pipe. At this time, under the action of the fluid pressure, a downward feedback force is applied to the piston axis, thereby preventing the bellows from continuing to deform axially.

[0013] Furthermore, the cooling assembly includes a bottom pipe sleeve, which is fixedly installed on the bottom end of the lower flange plate. The bottom pipe sleeve is a cavity structure, and an inner sealing ring is fixedly installed on the bottom end of the bottom pipe sleeve. A connecting pipe is fixedly connected to the outer side of the bottom pipe sleeve, one end of the connecting pipe is interconnected with the internal cavity of the bottom pipe sleeve, and the other end of the connecting pipe is interconnected with the through hole.

[0014] Furthermore, an annular groove is provided on the outer side of the bottom pipe sleeve, an external sleeve is sleeved on the outer side of the bottom pipe sleeve, a connecting branch ring is provided on the inner side of the external sleeve, the connecting branch ring is fixedly sleeved with the annular groove, an outer sealing ring is fixedly installed on the bottom end of the external sleeve, an evenly distributed heat dissipation grid layer is provided on the outer side of the external sleeve, and coolant is stored inside the external sleeve. When the bellows undergoes axial deformation to cause the piston shaft to move upward in the cavity cylinder, the bottom end space of the cavity cylinder expands, so that the material in the internal space of the bottom pipe sleeve is extracted through the connecting pipe, so that the coolant in the external sleeve is sucked into the internal space of the bottom pipe sleeve through the annular groove, thereby cooling the temperature of the fluid flowing therethrough to prevent its temperature from being too high. When the bellows is deformed and reset, the coolant inside the bottom pipe sleeve is pushed back into the external sleeve, the contact area between the external sleeve and the bottom pipe sleeve is small, and the heat dissipation grid layer can be used to exchange heat with the external environment for re-cooling.

[0015] Technical effects and advantages of the present invention:

[0016] 1. The present invention is provided with an over-compensation protection component. Under the action of fluid pressure, the bellows undergoes axial deformation to provide length compensation for the pipeline. During its deformation process, the distance between the upper flange plate and the lower flange plate gradually increases, and the piston shaft begins to move upward in the cavity cylinder. At this time, the gas or fluid in the upper end space of the cavity cylinder will be discharged outward through the leakage hole, thereby maintaining the gas pressure in the upper end space of the cavity cylinder stable. When the pressure of the fluid flowing through the inside of the bellows is too large and causes the bellows to reach its maximum allowable deformation, the pressure relief valve is opened, the sealing plate moves to the upper end to completely block the leakage hole, and the fluid passes through the pressure relief valve and the pressure relief hole and enters the upper end space of the cavity cylinder through the pressure relief pipe. At this time, under the action of the fluid pressure, a downward feedback force is given to the piston axially, thereby preventing the bellows from continuing to deform axially. In this way, the device realizes an over-compensation protection function adapted to the fluid pressure in the pipe.

[0017] 2. The present invention is provided with a cooling assembly. When the bellows is axially deformed so that the piston shaft moves upward in the hollow cylinder, the bottom space of the hollow cylinder expands, so that the material in the internal space of the bottom sleeve is extracted through the connecting pipe, so that the coolant in the external sleeve is sucked into the internal space of the bottom sleeve through the annular groove, thereby cooling the fluid flowing therethrough to prevent it from being too hot. When the bellows is deformed and reset, the coolant inside the bottom sleeve is pushed back into the external sleeve. The contact area between the external sleeve and the bottom sleeve is small, and the heat dissipation grid layer can be used to exchange heat with the external environment for re-cooling. In this way, the temperature cooling function of the fluid in the pipeline is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0019] Figure 2 It is a schematic structural diagram of the metal expansion joint assembly of the present invention.

[0020] Figure 3 It is a schematic diagram of the structure of the interlayer of the present invention.

[0021] Figure 4 It is a schematic diagram of the structure of the over-compensation protection component of the present invention.

[0022] Figure 5 It is a schematic diagram of the cross-sectional structure of the over-compensation protection component of the present invention.

[0023] Figure 6 It is a schematic diagram of the enlarged structure of the sealing portion of the present invention.

[0024] Figure 7 It is a schematic diagram of the cooling assembly structure of the present invention.

[0025] Figure 8 It is a schematic diagram of the cross-sectional structure of the cooling component of the present invention.

[0026] The accompanying drawings are marked as follows: 1. Metal expansion joint assembly; 101. Upper flange plate; 102. Lower flange plate; 103. Threaded hole; 104. Protective pull rod; 105. Protective nut; 106. Spacer; 107. Bellows; 108. Pressure relief hole; 109. Pressure relief valve; 2. Over-compensation protection assembly; 201. Bottom connecting column; 202. Through hole; 203. Column sleeve; 204. Cavity column; 205. Piston shaft; 206. Upper connecting column; 207. External leakage hole; 208. Thin shaft; 209. Sealing piece; 210. Pressure relief pipe; 3. Cooling assembly; 301. Bottom pipe sleeve; 302. Inner sealing ring; 303. Connecting pipe; 304. Ring groove; 305. External sleeve; 306. Connecting support ring; 307. External sealing ring; 308. Heat dissipation grid layer. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. In addition, the forms of the various structures described in the following embodiments are only examples. The metal expansion joint for low-temperature environments involved in the present invention is not limited to the various structures described in the following embodiments. All other embodiments obtained without creative work by ordinary technicians in this field belong to the scope of protection of the present invention.

[0028] Reference Figure 1 The present invention provides a metal expansion joint for low temperature environment, comprising a metal expansion joint assembly 1, the outside of the metal expansion joint assembly 1 is fixedly installed with evenly distributed over-compensation protection assemblies 2, and the bottom end of the metal expansion joint assembly 1 is fixedly installed with a cooling assembly 3;

[0029] In this embodiment, the metal expansion joint assembly 1 is used to connect the pipelines at both ends and compensate for the length of the pipelines through its own deformation function. The overcompensation protection assembly 2 is used to provide an overcompensation protection function that is adapted to the fluid pressure in the pipeline. The cooling assembly 3 is used to perform cooling protection on the metal expansion joint assembly 1. The specific structure and working principle of the above-mentioned components will be described in detail later.

[0030] Reference Figure 2 and Figure 3 The metal expansion joint assembly 1 includes an upper flange plate 101, a lower flange plate 102 is provided below the upper flange plate 101, the upper flange plate 101 and the lower flange plate 102 are symmetrical up and down, and the upper flange plate 101 and the lower flange plate 102 are both provided with evenly distributed threaded holes 103, a protection rod 104 is connected between the upper flange plate 101 and the lower flange plate 102, and both ends of the protection rod 104 are threadedly sleeved with protection nuts 105, a sleeve 106 is fixedly connected to the bottom of the upper flange plate 101, a bellows 107 is fixedly connected to the bottom end of the sleeve 106, and the bottom end of the bellows 107 is fixedly connected to the lower flange plate 102, and the sleeve 106 is provided with evenly distributed pressure relief holes 108, and a pressure relief valve 109 is fixedly installed in each of the pressure relief holes 108;

[0031] In this embodiment, the bellows 107 may be axially deformed due to the pressure and temperature of the fluid in the pipeline, thereby providing length compensation for the pipeline system. The protective rod 104 can provide an over-compensation protection function to prevent it from excessive deformation.

[0032] Reference Figure 4-Figure 6The over-compensation protection component 2 includes a bottom connecting column 201, which is threadedly sleeved with the threaded holes 103 opened on the lower flange plate 102, and a through hole 202 is opened in the bottom connecting column 201. The upper end of the bottom connecting column 201 is fixedly sleeved with a column sleeve 203, and the column sleeve 203 is communicated with the through hole 202. The column sleeve 203 is fixedly sleeved with a cavity cylinder 204, and the cavity cylinder 204 is movably sleeved with a piston shaft 205. The upper end of the piston shaft 205 is fixedly sleeved with an upper connecting column 206, and the upper connecting column 206 is threadedly sleeved with the threaded holes 103 opened on the upper flange plate 101, The upper end of the cavity column 204 is provided with an external leakage hole 207, and the bottom end of the upper connecting column 206 is fixedly connected with a thin shaft 208, and the bottom end of the thin shaft 208 is provided with a sealing piece 209, and the sealing piece 209 is located in the upper end internal space of the cavity column 204, and the shaft diameter of the thin shaft 208 is smaller than the aperture of the external leakage hole 207. When the sealing piece 209 moves to the uppermost end, the external leakage hole 207 can be completely blocked, and the upper end of the cavity column 204 is connected with a pressure relief pipe 210, and the pressure relief pipe 210 is interconnected with the upper end space of the cavity column 204, and the pipe of the pressure relief pipe 210 is fixedly sleeved with the corresponding pressure relief hole 108;

[0033] In this embodiment, under the action of fluid pressure, the bellows 107 undergoes axial deformation to provide length compensation for the pipeline. During its deformation process, the distance between the upper flange plate 101 and the lower flange plate 102 gradually increases, and the piston shaft 205 begins to move upward in the cavity cylinder 204. At this time, the gas or fluid in the upper end space of the cavity cylinder 204 will be discharged to the outside through the leakage hole 207, thereby maintaining the gas pressure in the upper end space of the cavity cylinder 204 stable. When the pressure of the fluid flowing through the bellows 107 is too high and causes the bellows to When 107 reaches its maximum allowable deformation, the pressure relief valve 109 opens, and the sealing plate 209 moves to the uppermost end to completely block the leakage hole 207. The fluid passes through the pressure relief valve 109 and the pressure relief hole 108, and enters the upper end space of the cavity cylinder 204 through the pressure relief pipe 210. At this time, under the action of the fluid pressure, a downward feedback force is given to the piston shaft 205, thereby preventing the bellows 107 from continuing to deform axially. In this way, the device realizes an over-compensation protection function that is adapted to the fluid pressure in the tube.

[0034] Reference Figure 7 and Figure 8The cooling assembly 3 includes a bottom pipe sleeve 301, which is fixedly installed at the bottom end of the lower flange plate 102. The bottom pipe sleeve 301 is a cavity structure. An inner sealing ring 302 is fixedly installed at the bottom end of the bottom pipe sleeve 301. A connecting pipe 303 is fixedly connected to the outer side of the bottom pipe sleeve 301. One end of the connecting pipe 303 is interconnected with the inner cavity of the bottom pipe sleeve 301, and the other end of the connecting pipe 303 is interconnected with the through hole 202. An annular groove 304 is provided on the outer side of the bottom sleeve 301, an external sleeve 305 is sleeved on the outer side of the bottom sleeve 301, a connecting support ring 306 is provided on the inner side of the external sleeve 305, the connecting support ring 306 is fixedly sleeved with the annular groove 304, an outer sealing ring 307 is fixedly installed on the bottom end of the external sleeve 305, a heat dissipation grid layer 308 is evenly distributed on the outer side of the external sleeve 305, and a coolant is stored inside the external sleeve 305;

[0035] In this embodiment, when the bellows 107 undergoes axial deformation so that the piston shaft 205 moves upward in the cavity cylinder 204, the bottom space of the cavity cylinder 204 expands, allowing it to extract the material in the internal space of the bottom pipe sleeve 301 through the connecting pipe 303, so that the coolant in the external sleeve 305 is sucked into the internal space of the bottom pipe sleeve 301 through the annular groove 304, thereby cooling the temperature of the fluid flowing therethrough to prevent its temperature from being too high. When the bellows 107 is deformed and reset, the coolant inside the bottom pipe sleeve 301 is pushed back into the external sleeve 305. The contact area between the external sleeve 305 and the bottom pipe sleeve 301 is small, and the heat dissipation grid layer 308 can be used to exchange heat with the external environment for re-cooling. In this way, the temperature cooling function of the fluid in the pipeline is achieved.

[0036] Working principle of the present invention: under the action of fluid pressure, the bellows 107 undergoes axial deformation to provide length compensation for the pipeline. During its deformation process, the distance between the upper flange plate 101 and the lower flange plate 102 gradually increases, and the piston shaft 205 begins to move upward in the cavity cylinder 204. At this time, the gas or fluid in the upper end space of the cavity cylinder 204 will be discharged outward through the leakage hole 207, thereby maintaining the air pressure in the upper end space of the cavity cylinder 204 stable. When the pressure of the fluid flowing through the inside of the bellows 107 is too high and causes the bellows 107 to reach its maximum allowable deformation, the pressure relief valve 109 is opened, and the sealing plate 209 moves to the upper end to completely block the leakage hole 207. The fluid will pass through the pressure relief valve 109 and the pressure relief hole 108, and enter the upper end space of the cavity cylinder 204 through the pressure relief pipe 210. At this time, under the action of the fluid pressure, a downward feedback force is given to the piston shaft 205, thereby The bellows 107 is prevented from continuing to deform axially. In this way, the device realizes an over-compensation protection function adapted to the pressure of the fluid in the pipe. When the bellows 107 deforms axially so that the piston shaft 205 moves upward in the cavity cylinder 204, the bottom space of the cavity cylinder 204 expands, so that the material in the internal space of the bottom pipe sleeve 301 is extracted through the connecting pipe 303, so that the coolant in the external sleeve 305 is sucked into the internal space of the bottom pipe sleeve 301 through the annular groove 304, thereby cooling the temperature of the fluid flowing therethrough to prevent it from being too high in temperature. When the bellows 107 is deformed and reset, the coolant inside the bottom pipe sleeve 301 is pushed back into the external sleeve 305. The contact area between the external sleeve 305 and the bottom pipe sleeve 301 is small, and the heat dissipation grid layer 308 can be used to exchange heat with the external environment for re-cooling. In this way, the temperature cooling function of the fluid in the pipeline is realized.

[0037] Finally, a few points should be explained: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, which may refer to mechanical connection or electrical connection, or internal communication between two components, or direct connection. "upper", "lower", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may change;

[0038] Secondly: In the drawings of the embodiments disclosed in the present invention, only the structures related to the embodiments disclosed in the present invention are involved, and other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other;

[0039] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A metal expansion joint for use in a low temperature environment, characterized in that: It comprises a metal expansion joint assembly (1), wherein evenly distributed over-compensation protection assemblies (2) are fixedly mounted on the outside of the metal expansion joint assembly (1), and a cooling assembly (3) is fixedly mounted on the bottom end of the metal expansion joint assembly (1); The metal expansion joint assembly (1) comprises an upper flange plate (101), a lower flange plate (102) is provided below the upper flange plate (101), the upper flange plate (101) and the lower flange plate (102) are symmetrical in vertical direction, both the upper flange plate (101) and the lower flange plate (102) are provided with evenly distributed threaded holes (103), a protective pull rod (104) is connected between the upper flange plate (101) and the lower flange plate (102), and the protective pull rod (104) is provided between the upper flange plate (101) and the lower flange plate (102). Both ends of the rod (104) are threadedly sleeved with protective nuts (105); the bottom of the upper flange plate (101) is fixedly connected with a sleeve (106); the bottom end of the sleeve (106) is fixedly connected with a bellows (107); the bottom end of the bellows (107) is fixedly connected to the lower flange plate (102); the sleeve (106) is provided with evenly distributed pressure relief holes (108); and pressure relief valves (109) are fixedly installed in the pressure relief holes (108); The over-compensation protection component (2) comprises a bottom connecting column (201), the bottom connecting column (201) being respectively threadedly sleeved with a threaded hole (103) provided on the lower flange plate (102), a through hole (202) being provided in the bottom connecting column (201), a column sleeve (203) being fixedly sleeved at the upper end of the bottom connecting column (201), the column sleeve (203) being communicated with the through hole (202), a cavity column cylinder (204) being fixedly sleeved at the column sleeve (203), a piston shaft (205) being movably sleeved at the cavity column cylinder (204), an upper connecting column (206) being fixedly sleeved at the upper end of the shaft body of the piston shaft (205), the upper connecting column (206) being respectively threadedly sleeved with the threaded hole (103) provided on the upper flange plate (101). The upper end of the cavity column (204) is provided with an external leakage hole (207), the bottom end of the upper connecting column (206) is fixedly connected with a thin shaft (208), the bottom end of the thin shaft (208) is provided with a sealing plate (209), the sealing plate (209) is located in the upper end internal space of the cavity column (204), the shaft diameter of the thin shaft (208) is smaller than the aperture of the external leakage hole (207), the sealing plate (209) can completely block the external leakage hole (207) when it moves to the uppermost end, the upper end of the cavity column (204) is connected with a pressure relief pipe (210), the pressure relief pipe (210) is communicated with the upper end space of the cavity column (204), and the pipe of the pressure relief pipe (210) is fixedly sleeved with the corresponding pressure relief hole (108).

2. A metal expansion joint for use in a low temperature environment according to claim 1, characterized in that: The cooling assembly (3) comprises a bottom pipe sleeve (301), the bottom pipe sleeve (301) being fixedly mounted on the bottom end of the lower flange plate (102), the bottom pipe sleeve (301) being a cavity structure, an inner sealing ring (302) being fixedly mounted on the bottom end of the bottom pipe sleeve (301), a connecting pipe (303) being fixedly connected to the outer side of the bottom pipe sleeve (301), one end of the connecting pipe (303) being interconnected with the internal cavity of the bottom pipe sleeve (301), and the other end of the connecting pipe (303) being interconnected with the through hole (202).

3. A metal expansion joint for use in a low temperature environment according to claim 2, characterized in that: An annular groove (304) is provided on the outer side of the bottom pipe sleeve (301), an external sleeve (305) is sleeved on the outer side of the bottom pipe sleeve (301), a connecting branch ring (306) is provided on the inner side of the external sleeve (305), the connecting branch ring (306) is fixedly sleeved with the annular groove (304), an outer sealing ring (307) is fixedly mounted on the bottom end of the external sleeve (305), a uniformly distributed heat dissipation grid layer (308) is provided on the outer side of the external sleeve (305), and a coolant is stored inside the external sleeve (305).

Images